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Topic: Engine pinging getting louder !! (Read 3468 times)

I canít quite put my foot on it. I have a 69 Camaro with a 406. I'm getting a heavy tick/ping when I start to accelerate at low RPM's and its getting louder. Here is whatís happening:

1. Slight ticking at low idle but gets louder with Rpm increase at stand still. Sounds like a deisel engine.2. Worst when engine is not fully warmed up it seems?3. When I start to move, it becomes louder until a certain sweet spot is reached on the gas.4. If I put the pedal to the floor or accelerate quickly and pull the RPM back and cruise, it goes away.5. The clack appears at the low end and high end of the RPM band, but when I cruise and hit that sweet spot the engine sounds normal.

At first I thought it was collector gasket or exhaust issue but I'm not sure anymore?Also, after a bit more investigation myself, I'm wondering if it can be piss poor premium Gas??

I always add a bottle of octane boost but might have easily not done it the last time I filled it up??

Are you running forged pistons? They need more bore clearance especially race forge, and clatter most when the engine is cold.Does it sound like the noise is from one place only, as in one clack per firing of only one cylinder, or does it sound like all cylinders are clattery?If it sounds like only one cylinder, you could try pulling each spark lead off in turn. If it's piston slap, the noise will disappear when you stop that cylinder from firing

That it happens at idle tends to rule out fuel/combustion pingAll of your points are typical of piston slap, except No 4, though it may be because of extra heating of the pistons making them expand a bit more and run quieter.